The commercial swimming pool pump market is defined by size, typically ranging from 5 HP to 25 HP. Previously, manufacturing a commercial swimming pool pump using an injection molding process was not practical due the relatively small market size, the capital investment required, and the technical challenges involved in commercializing an injection molded pump of suitable size. Commercial swimming pool pumps are typically constructed of either cast iron or cast bronze that weigh between 300-500 pounds. One disadvantage of commercial pumps is that they normally require special equipment such as a hoist or lift truck to install or replace the pumps. This is especially important when replacing pumps in an existing installation where access by a lift truck is no longer practical without removing facility doors or walls. Another disadvantage of commercial pumps is that they can be susceptible to corrosion, which can cause vital pump components to fail and ultimately shutting down the pump and the pool. In addition, the corroding components deposit chemical materials into the water where they come into contact with the swimmers. Furthermore, the corroding components can deposit permanent chemical stains on the pool walls.
Another disadvantage of cast pumps is that the cast components are cast to a rough size and finish. Therefore, cast components require additional machining to shape and finish the components. Whereas, injection molded components are molded to the correct size and finish.
Still another disadvantage of cast pumps is the inherent defects that are present in the metal casting process. These defects include pinholes, poor surface finish, and rapid surface oxidation. Typically, cast components are reworked to repair these defects thereby adding cost to the manufacture of such pumps. In addition, detection of pinhole leaks does not typically occur until the pump is in operation thus requiring the pump and pool to shut down during repair.
In order to overcome the above mentioned disadvantages, commercial swimming pools typically utilized multiple small, injection molded, residential pumps, usually limited to 3 HP, to obtain the benefit of using a light weight, corrosive resistant pump. However, the costs associated with installing and maintaining multiple pumps were not cost effective.
In addition, one challenge in manufacturing large injection molded parts is the difficulty in molding an open end of a large cylindrical shaped part with a high degree of roundness. Another challenge is that it is difficult to mold a flat plate type geometric shape such as a pump seal plate to a controlled tolerance of flatness. These, geometric shapes tend to move during operation of the pump due to the stresses on the seal plate and housing cylinder.